Go to the part of the map where the windows are. You need two players.

One player buys a turret and sets it down. The other gets on the turret.

The person who bought the turret then picks up the turret and the guy should be on the turret still.

Then move the turret into the glass (or the wall beneath it) and when the guys body is through the wall, the person on the turret turns in to oracle mode and lags through.

Don't go past the pipes, you will die.